基于打印机\绘图\文本手册
该函数使用所选字体在x、y位置绘制文本。
在你的代码里 x,y 值为10,10。所以每次新的文本都写在同一个位置上。这意味着上一个值被新值覆盖，并且只绘制一个值。
有两种可能solution:-
1.每次迭代后改变x，y位置值。

$counter = 10; //add a number counter

while ($fetch = mysql_fetch_assoc($myquery)) {//use assoc for lighter array iteration

    $product=$fetch['product_name']; //use quotes around indexes, best practise
    $type=$fetch['type'];
    $q=$fetch['item_quantity'];
    $comment=$fetch['comment'];

    $tex="$q $type $comment $product";//remove unncessary quotes
    printer_draw_text($handle, $tex, $counter, $counter); // use that number counter as x,y position
    $counter+10;//in each iteration chnage the value by adding 10
}

2.或在每个页面中创建新页面iteration:-

while ($fetch = mysql_fetch_assoc($myquery)) {//use assoc for lighter array iteration

    $product=$fetch['product_name'];//use quotes around indexes, best practise
    $type=$fetch['type'];
    $q=$fetch['item_quantity'];
    $comment=$fetch['comment'];

    $tex="$q $type $comment $product";//remove unncessary quotes
    printer_draw_text($handle, $tex, 10, 10);
    printer_end_page($handle); //end page on each iteration
  }
printer_delete_font($font);
printer_end_doc($handle);
printer_close($handle);

note:- add 代码的其余部分。